The Tohono O’Odham Nation government vows strong opposition to President Donald Trump's border wall, but the Arizona tribe's biggest border problem actually may be Mexico.

More specifically, it appeared to a New Times reporter watching from the U.S. side this past weekend that Mexico is ignoring suspicious activity on tribal land south of the border, including armed men traveling in military-style Hummers.

Ray Stern has worked as a newspaper reporter in Arizona for more than two decades. He's won many awards for his reporting, including the Arizona Press Club's Don Bolles Award for Investigative Journalism.